The inadvertent exposure of the spinal cord to the water soluble X-ray contrast media during radiologic procedures is an extremely serious, sometimes fatal complication. We will induce spinal cord injury in dogs and rabbits by exposure to contrast agents by both direct (Intrathecal) application and by retrograde aortography. The pathogenesis and pathophysiology of the developing lesion will be followed by electron microscopy. Fluorescence analysis will be made of the catecholamine content of the injured tissue. The value of adrenergic blockade alone, or combined with steroids (methylpredniosolone) on the clinical recovery of the injured animals will be determined by assessment of improvement in motor performance. The objective is to determine the role of vasospasm in the production of the contrast medium-induced lesion and the clinical value of the pharmacologic relief of the vasospastic phenomenon.